Tools are well known that combine an adjustable or rotatable tool head with a rod to extend a person's reach. Examples of such tools include a rod-borne drywall finishers, cement and plaster trowels, sanders, squeegees, and the like. Typically the tool head is made adjustable or rotatable relative to the rod in order to enable the head to assume a suitable position relative to a work surface. For example, the tool head of a typical rod-borne drywall finisher is tiltable in a manner which enables the flat tool surface of the head to be positioned parallel to the drywall surface.
Some such known tools are provided with linkages which permit the selective positioning of the tool head in response to a simple and convenient squeezing or closing motion of the operator's hand on a handle at the grip end of the rod, remote from the tool head. The manually squeezable handle is connected by one or more linking members to a lock mechanism which locks or unlocks the head in selected angular positions. A problem with these known types of mechanisms is that the linkages have not been satisfactorily incorporated in a tool that also has a telescoping, adjustable-length extension rod. Although a telescoping rod having a tool head which is controllable from a remote end of the rod is seen in U.S. Pat. No. 2,834,199 (Freeman), the tool shown therein sacrifices the squeezable handle and linkage. Rather, the Freeman device, a tiltable head 10 is pivoted to the desired tilt angle by rotating or twisting the rod 37, which requires twisting by the person's hands. Consequently, this adjustment cannot be achieved by a simple and convenient squeezing motion.
Other devices are known for remotely controlling the positioning or operation of tool heads mounted on extension rod, however, these also fail to show any such mechanism which can be operated by a simple squeezing motion of the operator's hand and which can be used in combination, with an adjustable-length extension rod:
U.S. Pat. No. 4,819,293 (Nicholson) shows a pull ring 68 connected to a wire 66 which runs internally through a pole to a pin member 58 for locking and unlocking a rotatable head 42.
U.S. Pat. No. 4,702,641 (Naser et al) shows a concrete working tool wherein rotation of the pole actuates a worm gear and a toothed rack to cause the head to assume various angular positions.
U.S. Pat. No. 4,335,485 (Paine et al) shows another trowel wherein rotation of the pole rotates a worm gear which turns another gear which causes the head of the tool to assume different tilt angles.
U.S. Pat. No. 3,616,483 (Mantelet) shows, in a first embodiment (FIG. 6) a rotatable crank handle 16 which turns a pinion which moves racks 56, 58 in opposite directions, this causing an internal cable 60, 62 to rotate a gear 66 which wrings a mop head. In a second embodiment (FIG. 9), movement of a slideable outer sleeve handle 70 pulls an endless cable 72 to rotate gear 66, which again wrings the mop head.
U.S. Pat. No. 3,146,4891 (Chiuchiarelli) shows a concrete trowel in which rotation of a pole causes the angular position of the trowel head to change. In this case concentric threaded sleeves form an assembly which extends from the end of the pole and which changes length when the pole is rotated, so as to pivot a trowel head which is pivotably mounted at spaced-apart points to this assembly and to a fixed-length connector 17.
U.S. Pat. No. 2,861,287 (Scalf) shows a pole having a handle 30 at its end which is connected via an internal cable to a lock mechanism which locks and unlocks a mop head as the handle is pulled.
U.S. Pat. No. 2,607,363 (Frey) shows an umbrella pole in which an angular position of the umbrella is changed by means of an internal linkage which is actuated by a rotatable handle.
U.S. Pat. No. 1,162,845 (Armstrong) shows a grippable lever 26 which operates a cable which extends along a fixed-length shovel handle 11 to lock an adjustable shovel head in various angular positions.
U.S. Pat. No. 2,221,219 (Nelson), U.S. Pat. No. 1,741,004 (Wornstaff) and U.S. Pat. No. 1,261,859 (Seiter) show other shovels in which a linearly movable rod or wire which extends along a fixed-length handle is moved to lock and unlock a pivotable shovel head in various positions at the end of the handle. In Wornstaff the rod is actuated by a hand lever 17.
Accordingly, there exists a need for an effective and reliable mechanism which combines an adjustable-length extension rod with a squeezable handle and linkage for remotely controlling the positioning and locking and unlocking of a tool head which is mounted at one end of the rod, and, among other things, for a suitable handle mechanism that is able selectively operate such a linkage.